1. Technical Field
The present invention relates to a technique for activating a device in a power-saving mode when a host apparatus and a device are connected together by a communication system which assigns the host apparatus as a master and the device as a slave.
2. Related Art
A device, such as a printer, connected to a host apparatus establishes a power-saving mode when there is no access from the host apparatus over a prescribed time period. Such a configuration is disclosed in, for example, International Patent Publication No. WO00/28402.
However, when the host apparatus and the device are connected to each other by a USB (Universal Serial Bus), the following problems arise. Specifically, according to the USB, communication is effected while the host apparatus is acts as a master and the device acts as a slave. Accordingly, the host apparatus in principle causes the device to check, at a short cycle, a status and whether or not a request to the host apparatus is present.
Therefore, the device connected to the host apparatus by the USB frequently receives inquiries from the host apparatus, which hinders the device from establishing a power-saving mode.